12th (Converted) Gunboat Division — 1942

[Leo Niehorster]

Greetings,
Ran across a mysterious unit. It is only named late March 1942 under the 1st Burma Convoy (Japanese Monograph 97) and once under the Southwest Area Fleet, 12th Special Base Force (Japanese Monograph 116) between 15.02.42 and 10.04.42, when it was deactivated. Interestingly enough, it is not listed in JM 116 under the Gunboat Divisions in Part VI: "Organization of the Naval Ship Divisions".

Would appreciate any information, particularly regarding the commanding officer, and especially its three (?) gunboats.

Cheers
Leo

[hisashi]

Capt.Mori Kunizo(later VAdm) commanded converted minesweeper-tender Nihonkai-Maru from 15 Dec 1938 to 1 Apr 1939. Concurrently he was appointed as the CO, 13th gunboat division (hoteitai). In 1 Mar 1939 Nihonkai-Maru laid aboard '1st group(dai-1 shotai)' They were daihatsu and shohatsu, in total 6. So we can imagine at least 12 boats of daihatsu-shohatsu size.
http://www.geocities.jp/tokusetsukansen ... 07_002.htm

Interestingly In 18 Dec 1938, after he took on 13th hoteitai, crews of 12th hoteitai got off Nihonkai-Maru. It was recorded Nihonkai-Maru accepted wounded men and deads of 12th hoteitai a few times during the days of Mori's predecessor, Cmdr.Murayama Seiroku.

There were dozens of (70-80?) purpose-built gunboats. '25t type' gunboat's spec was 17m length, 150HP engine x2, one 13mm MG. If refit for a 13mm MG, daihatsu, shohatsu and tokudaihatsu were similar ones in size, but slower from lower engine power.

War diaries of 52nd hoteitai survived the war relatively well, for many months. They stationed O-Minato port mainly for minesweeping. In 1944 they had six tokudaihatsu (judging from their 80HP engine) armed with 13mm MG (they were issued 12 MGs so maybe two for each) and the CO of 52nd was concurrently the skipper of Minelayer Tokiwa. 52nd hoteitai had 6 officers but 4 of them were concurrent appointment in Tokiwa crew.

It may happen that 12th, in question, had some converted boats, but anyway they would be comparable to daihatsu in size. And they were so few in personnel that they must mistletoe large ship or ground force for their administration. It looks one reason why hoteitai COs are diffecult to find out. When they went to new battlefield, somebody there was assigned to take care of them as a CO.

Available 12th SBF's war diary are scarce. But in Jul 1943 they had '4 small gunboat and 1 medium gunboat ' under direct control of 12th SBF HQ.

In Navy's account on Burma/Andaman Occupation JACAR C14061111400 C14061130900, 12th Hoteitai was under 12th SBF, with '4 daihatsu and 1 captured boat'. So in effect they were in Andaman after disbanded as a hoteitai. 12th SBF did not have large tender ship, so I guess RAdm Ishikawa Shigeru, CO 12th SBF, took on CO 12th hoteitai for a while in 1942, but I am not sure.

[Leo Niehorster]

Thank you very much for your time and detailed reply.
Cheers
Leo